- Due to their large population, Nematodas have a short life span, so their population levels change in large numbers, weekly.
- Nematodes are dioecious, with separate male and female genders.
- There are four stages of a nematodes life: egg stage , four larval or juvenile stages, and an adult stage.
- During each juvenile stage, a molt happens where the cuticle is shed, allowing the nematode to increase in size.
- Plant-parasitic nematodes pass through the juvenile molt, without hatching from the egg.
- Mild to warm temperatures, 55-65º F are optimal developing temperatures. Soil moisture and food availability also affect a nematodes development time.
- The male is smaller than the female, and using its bent tail to hold the female, injects sperm into the female ovary, to fertilize an egg.
- Eggs are protected with an outer shell, and after some development, hatch into larvae.
- Eggs can hatch in a variety of ways such as: the nematode-baterium complex cycle (see below), or the egg being held in the uterus until hatching, which can sometimes result int the juvenile nematode eating its parent nematode after hatching, or sometimes the egg will develop in another organism or plant.
- This image displays the nematode-bacteruim complex cycle.
- Infective juveniles seek out an insect host, and enter into the body cavity through openings.
- A symbiotic bacterium is released, which multiples and rapidly kills the host.
- Nematodes feed on the bacteria and liquefy the insect host.
- The mature into adult male or females and leave the host.
- The cycle is completed within a few days.
- Nematodes growth all depend on the conditions inside the host.
- First stage larvae develop inside an egg, then hatch.
- Newly hatched larvae feed on bacteria and grow until their outer skin or cuticle constrains them.
- A nematode can continue to grow only if it sheds its old outer cuticle, and grows a new, more flexible cuticle.
- This is the process of molting and involves two steps:
Exsheathment: process where the old cuticle is loosened and fractured, followed by c the larvae wiggles out of the old cuticle's casing.
- This represents the developmental stages of the nematoda.
- The parasitic phases happen inside the host. The pre-parasitic phases occur as a free living phase in the outdoor environment or inside an intermediate host, a second host.
- The basic life cycle consists of seven stages, the egg stage, four larval stages (L1, L2, L3, L4), and two adult stages, creating male and female populations. The L5 stage is for sexually immature nematodes.
- Most sexual reproduction happens within another host.
- The development of a nematode represented by a growth curve:
- L1- nematode develops inside an egg
- H- hatches
- M1- grows quickly and molts
- L2- another rapid growth spurt
- M2- transitions into a second molting
- L3- third larvae stage, the infective stage for many species
- M3- Grows and molts
- L4- final larvae stage inside the host
- M4- nematodes final molt
- Adult- immature adult stage, pass throughout L5's as a final growth stage, when they become sexually mature.